We've been Waterloo-ed

We've all been told that you must drink at least 8 glasses of water per day to stay healthy and "hydrated." Here in Phoenix, with temps in the triple digits for 4-5 months each year, it is a canonical article of faith. But as Kevin Drum has re-discovered, there is no scientific basis for it per recent studies. He writes: "So how much water should you drink? Answer: as much as you want. If you're thirsty, drink some water. If you're not, don't bother. And "water" includes coffee, tea, soft drinks, and pretty much any other water-based beverage. Water with caffeine in it is just as good as water without it." I guess Mark Twain got it right after all when he said, "Water, taken in moderation, cannot hurt anybody."